(1) Field of the Invention
The present invention relates to maxillofacial surgery. Specifically, it relates to stabilizers for positioning and stabilizing fractured or surgically mobilized bony structures and, more specifically, to a stabilizer for bony structures such as the midface/maxillae and mandible for use in maxillofacial surgical procedures.
(2) Description of Prior Art
Facial and mandibular bones may be broken up for surgical purpose or accidentally in a traumatic injury. There are a variety of cranio-facial procedures available for trauma and malformation in which the broken bones are re-connected together to achieve both function and cosmetic results. Currently, these procedures are performed by surgeons and one or more surgical assistants. The surgeon will manually position the bone to the best possible alignment, and the broken pieces are then connected using metal plates and screws. The conventional approach to positioning, orienting, and stabilizing the unstable or mobile bone segments is completely by hand, with minimal or no instrument assistance. The examples of instrumental assistance including splits made with dental castings. Such manual manipulation for finding the best fit of the segments often requires several consecutive maneuvers in a repetitive pattern, and can be challenging for the surgeon. At the very least it diverts the surgeon's concentration, efforts and time away from the procedure itself. This loss of focus can result in suboptimal results, such as limited movement and facial dimensional imbalance and/or asymmetry.
To aid the manual orientation, positioning and fixation process, surgical planning systems were proposed. For example, U.S. Pat. No. 7,792,341 to Filip Schutyser proposes a surgical planning system that uses three-dimensional images of the patient to create three-dimensional surfaces of structures in the maxillofacial region and generate two-dimensional images (cephalograms). Such image manipulation allows the analyses and planning of the maxillofacial surgical procedures. The output from such maxillofacial surgery planning system can be the parameters for making plaster molds, making surgical splints, or to a computer display that simulates the procedure as a means of navigating the surgeon through the manipulation process (see, e.g., FIG. 13 and FIG. 15 of U.S. Pat. No. 7,792,341). Although such planning is useful in making the necessary molds and splints to aid the procedure, it does not help in the actual manipulation process. It also does not provide the guidance for fine tuning and adjustment before fixation.
Ideally, the positional accuracy and the match to the original geometry (in the case of a trauma) or the newly obtained facial symmetry (in the case of a malformative syndrome) should be established by standard anthropometric analysis using precise anthropometric measuring tools, and then verified radiologically prior to fixation with plates and screws. However, this is not possible when the bone pieces are being held together by hand. Similarly, surgical residents cannot learn the skills if they cannot see the surgery because the surgeon is hovering over the patient.
What is needed is a stabilizer device to make the procedure less operator dependent, to allow objective verification of the bone positioning and fine adjustment prior to fixation, and to allow trainees in the room to view the positioning and orientations of all bone pieces before they are screwed together.
Headframes for stereotactic neurosurgery and radiosurgery are well known. These headframes are ring-shaped structures which are mounted to the skull of a patient to provide a fixed reference with respect to the patient's skull. A typical stereotactic head frame is a halo affixed to a patient's skull (under anesthesia) using pins or screws. The stereotactic frame may also act as a guide for delivering various instruments such as a biopsy needle or DBS leads or electrodes. FIGS. 1-3 are a front perspective view, top view, and side view, respectively, of a prior art head frame as shown in U.S. Pat. No. 7,925,328 to Urquhart et al. issued Apr. 12, 2011. The frame 1 is attached to a patient's skull with three screws 2 fixed into the frontal outer cortical bone/outer layer. Such devices offer accurate neurosurgical localization during procedures such as stereotactic cranial biopsy and cranial surgery. For example, for radiosurgery of intracranial lesions, a head frame is used to localize the lesion and to position the lesion at the center of the radiation focus. See, Leksell, L., “Cerebral Radiosurgery. I. Gammathalmotomy In Two Cases Of Intractable Pain”, Acta chirurgica Scandinavica, vol. 134, p. 585-595; 31 (1968). However, such head frames have not been suggested or used for aiding maxillofacial or cranio-facial surgery. A common drawback of the frames disclosed by Urquhart et al and Leksell is that these frames cannot be adjusted to the head size and shape and they interfere with the maxillofacial surgeon's work.
During maxillofacial trauma procedures and orthognathic/malformative procedures, the positioning, orienting and stabilizing (POS) of unstable/mobile bony segments are performed manually by surgeons without instrumental aids. Such maneuvers are often tiresome and time consuming. Human hands often lack long-term consistency, stability and strength, and so clinical results are often operator dependent. Other drawbacks of the current practice include the infeasibility of position verification before fixation, and the limited teaching/education capacity. These are all factors that can interfere, affecting that final position of the skeletal segment and leading to undesired results, such as asymmetry and suboptimal chewing function.
In view of the foregoing, the present disclosure provides a method and device for positioning and stabilization of bony structures during maxillofacial surgery that improves clinical performance of surgeons by freeing the surgeon's hands so that two-dimensional or three dimensional radiological images can be taken and verified against prior image sets and/or reference data. It is also the objective of the present disclosure to allow very fine adjustments to a stabilized arrangement of bony segments if desired prior to bone fixation. The device frees the surgeon's hands and makes their task less strenuous, more accurate, easier and efficient. The device is specifically configured to stabilize the mandible and/or the upper pallet for the purpose of maxillofacial and cranio-facial surgery without interfering with the procedure or anesthesia equipment.